Impose equations on different subdomains from xml mesh

[dokken]

See for instance this demo. However, i would advice you to But use xml, But xdmf, as described in these two posts :

Converter from GMSH to XDMF (with physical groups)

Hello, I recently had to import GMSH mesh in Fenics, so I wrote a small script to ease the import. This script uses meshio to convert a GMSH mesh file (msh2, msh40, msh41) into two XDMF files: one for the domain and another to store the physical groups defined in GMSH. There is also an utility function returning the Mesh and the MeshFunction associated to those files. The script and more details about its usage are available at: https://github.com/floiseau/msh2xdmf. Feel free to recommend any…

and

Transitioning from mesh.xml to mesh.xdmf, from dolfin-convert to meshio

@fforteneto, After some help from @nschloe, the following code will work with the newest meshio: import meshio msh = meshio.read("mesh.msh") for cell in msh.cells: if cell.type == "triangle": triangle_cells = cell.data elif cell.type == "tetra": tetra_cells = cell.data for key in msh.cell_data_dict["gmsh:physical"].keys(): if key == "triangle": triangle_data = msh.cell_data_dict["gmsh:physical"][key] elif key == "tetra": tetra_data = msh.cell_da…